Printing method and means



M A H R U D N H PRINTING METHOD AND MEANS Filed May 10, 1939 ATTORNEY.PatentedMay 25, 1943 ram-rule METHOD AND MEANS Hobart N. Durham,Manhasset, N. Y., assignor to The Goss Printing Press Company, Chicago,111., a corporation of Illinois Application May 10, 1939, Serial No.272,822

Claims.

The invention relates to new and useful improvements in method and meansfor printing and drying printed surfaces, and more especially to suchmethod and means for very rapidly drying printed surfaces in fast rotarypresses. the invention being especially useful in fast rotary multicolorprinting.

The invention consists in the novel methods, steps, sequences,mechanisms and combinations disclosed in the specification and pointedout in the appended claims.

Objects and advantages of the invention are set out in part hereinafter,and in part will be obvious to those skilled in the art or may belearned by practice with the invention.

The accompanying drawing, referred to herein and constituting a parthereof, illustrates one mechanical embodiment of the invention and onemanner, of carrying out the method of the invention.

Of the drawing:

Fig. 1 is a diagrammatic elevation of a perfecting multi-color rotarypress for relief printing, embodying the invention; and

Fig. 2 is a fragmentary, detail section on lines 22 of Fig. l.

Objects of the invention are to provide method and means for rapidlyprinting and easily and quickly drying inked impressions on a surface,and more especially quick and easy drying of impressions made on paperwebs running through fast rotary presses. both in single color andmulticolor printing; to provide such method and means which effectpractically instantaneous drying without requiring wetting of the paperor its being subjected to sudden and violent temperature changes, thusavoiding consequent shrinkage, warping or other impairment of the websresulting in poor register, strains and deformations in the webs, whichespecially militate against the best results, especially in certaintypes of multi-color printing; to provide such method and meansapplicable to the various kinds of printing including printing on fastrelief and intaglio presses; to provide such method and means whichavoid the necessity of high temperatures in press rooms, or in fact, anychange in press room temperatures, and substantially avoid or eliminatefumes from the press room atmosphere, and likewise avoid the use uponthe webs of flame, steam, strong air blasts and like forces andagencies; to provide method and means for rapidly printing and almostinstantaneously drying the freshly printed webs by instantaneousebullition of the volatile solvent in the ink on the web, by presentingthe freshly printed impressions in an atmosphere below the vaporpressure of said volatile solvent at the printing locus, whereby thesolvent flashes into vapor, as distinguished from usual drying byevaporation, burning, absorption, or oxidation, with the vapor pressurebelow the drying pressure; to provide, when desired, as auxiliary dryinagencies, relatively mild heat or air currents to a limited extent, toassist in the drying operation; to provide such method and means for usein a press room operating under normal atmospheric and temperatureconditions, wherein the freshly printed surfaces are presented in anatmospheric pressure substantially below the vapor pressure at the pressroom temperature of the volatile solvent component of the ink; toprovide rotary press structures and arrangements adapted for thepractice of the method in relief, intaglio or other kinds of printing.

Referring now in detail to the embodiment of the invention, illustratedby way of example in the accompanying drawing, the invention is shownapplied to a perfecting multi-color rotary relief press of the typewherein a plurality of plate cylinders, each having its own inkingsystem, ooact as printing couples with a single large impressioncylinder, and the web after being printed in multi-color on one side isdirected to a similar mechanism to be perfected in multi-color. In saidembodied form, each printing unit comprises an impression cylinder l andcoacting therewith are shown four plate cylinders 2, 3, l and 5,provided. respectively, with inking mechanisms 6, I, 8 and 9. Theweb was it goes through is printed in four colors in a known manner.

The immediate or quick dryingof the colors on the freshly printed web iseffected entirely or principally by causing ebullition under reducedpressure of the highly volatile solvent in the printing ink. Theinvention finds one of its principal and most useful applications infast rotary printing with the modern quick-drying inks. These inkscomprise a coloring pigment or dye, a binder and a highly volatilesolvent which has a high vapor pressure at usual or normal press-Acetone 2o; 185 so 283 Millimeters Means are provided by the inventionfor immediately subjecting the freshly printed surface of the web to anatmospheric pressure which is substantially below the vapor pressure ofthe volatile solvent in the ink at the temperature of the printinglocus. In the embodied form of said means, a chamber is provided withinwhich the required lower atmospheric pressure may be maintained, and thefreshly printed web is led immediately thereinto. This results inimmediate ebullition of the volatile solvent component of the ink, thatis, it flashes into vapor, leaving the dry pigment and othernon-volatile ink components as the design. This is effected withoutwetting the web, without subjecting it to either high or low temperaturechanges, or to flame or to strong air blasts; in fact, the web is leftin its normal condition and not subjected to disturbing anddeteriorative influences and changes that impair registration or otherrequisites of fine printing.

This low atmospheric pressure chambers, as embodied, comprises arelatively large drum 20 located near to the point of emergence of theweb from the printing cylinders, the web being directed around thecylinder 20 for a large portion of its periphery. An almost completelyclosed chamber is formed around the cylinder 20, coincident with thepath of travel of the web, and as embodied, a cylindrical plate 2|encircles a large part of the cylinder 20, and is spaced away therefromso as to provide a chamber 22 between them. Seals are provided at eitherarcuate endof the plate 20, cooperating with the flat ends of thecylinder 20, and are shown as arcuate plates 23 fast to and extendingfrom the arcuate edges of plate 2|, and having at their inner curvededges sealing members 24 abutting on and sucked against the fiat ends ofcylinder 20. The suction within the chamber 22 draws the sealing membersin tightly against cylinder 20, to form effective air seals. At thestraight edges of the plate 2 I, which constitute the limits of thechamber 22, are closure plates 21 fixed to the straight edges of plate2| and directed inwardly toward the drum 20, leaving just enoughclearance for the web w to pass between the edges of the plates and thesurface of the drum. Thus the cylindrical plate 2|, the side sealingplates 22 and the end plates 21 constitute a housing or closure aboutdrum 20 within which the low atmospheric pressure is maintained.Air-exhausting means are provided exerting any desired degree of suctionon the chamber 22, thereby to reduce the atmospheric pressure thereinbelow the vapor pressure for the volatile solvent at the existenttemperature, and as embodied, a pipe 29 communicates preferably with thecentral part of the chamber 20, and a pump 30 driven by a suitable motor3| exhausts air from the chamber 22. This air carries off the vapors ofthe solvent as they are created within the chamber 22, and they areconveyed by a pipe 32 to any suitable recovery means.

There are preferably provided, as additional closure or air seal meansfor the chamber 22, at either end thereof, a plurality of vanes 31,fixed to the inner face of the cylindrical member 2|, and extendingentirely across chamber 22. The vanes are preferably in side-by-side,parallel. spaced-apart relation, and directed toward the drum 20, butleaving a minimum clearance for the passing web w, the vanes beingpreferably in a non-radial relation. Because of the reduced atmosphericpressure within the chamber 22, air turbulence is created between andabout the vanes 31 which impedes entrance of air, and acts to a largerextent as a sealing means, contributing to maintain the required loweratmospheric pressure within the chamber 22. At the same time thispermits the passage of minute or very thin, sheet-like currents of airat high velocity which participate in the drying action, the main partof which, however, is effected by the ebullition of the solvent in thelow pressure atmosphere of the chamber 22.

As an optional feature of the invention additional drying means may beprovided within the chamber 22, although normally this will not berequired and may not even be desirable. For this purpose, if desired,elements effecting mild heating action within the chamber 22 may beemployed, as for instance, radiant heaters or infrared heaters 38. Thisauxiliary heating action,

if and when used, will exert a temperature effect on the web which isrelatively mild and not sufficient to cause physical changes in the websuch as shrinking, or cause undue heating of the press room. The purposeof such auxiliary means is to raise the temperature of the web merelysufficient to raise the vapor pressure somewhat of the ink and toovercome the heat loss caused by the ink evaporation.

In accordance with one feature of the invention, temperature reductionmeans are applied to the inking mechanisms for the plate cylinders 2, 3,4 and 5, either in groups or to various mechanisms singly, to providesuificient chilling to prevent uneconomical evaporation of the inksolvent in the fountains or on the various members of the inking system.As here shown, each inking system is enclosed within a casing 4|, eachsuch casing consisting wholly or partly of removable plates or members42, whereby ready access can be had to the inking system for regulation,cleaning or other purposes. The inking systems there shown are of thetype wherein the entire system is movable on the press frame intooperative relation with the plate cylinder and also movable awaytherefrom to an accessible cleaning position. As shown, each of thecasings 4| is provided with a plurality of refrigerating coils 43connected by pipes 44 to a suitable refrigerating device 45.

It will be clear that the low atmospheric pressure chamber can beapplied in like manner to other types of presses, such as rotogravurepresses, or others, by leading the web from a printing couple into achamber such as the chamber 22 which will operate in the mannerhereinbefore described.

The invention consists in the novel steps, sequences, elements andcombinations as pointed out in the accompanying claims, and it will beunderstood that departures may be made from the specific forms shown anddescribed without departing from the principles of the invention andwithout sacrificing its chief advantages.

What I claim is:

1. The method which comprises printing on a surface with an inkincluding a non-volatile color and a highly volatile solvent, andintroducing said freshly printed surface into a lower pressure zone at atemperature below the boiling point at normal atmospheric pressure ofthe ink solvent, the pressure in said zone being sufficiently below thevapor pressure of said solvent to effect ebullition of the ink solvent.

2. The method which comprises printing on asurface with an ink includinga non-volatile color and a highly volatile solvent at a givenatmospheric pressure and immediately presenting the freshly printedsurface in zone of less pressure at a temperature below the boilingpoint at normal atmospheric pressure of the ink solvent, the pressurebeing substantially below the vapor pressure of the solvent at thetemperature of said zone to effect ebullition of the ink solvent.

3. The method which comprises printing on a surface with an inkincluding a non-volatile color and a highly volatile solvent,maintaining a chamber having a lower atmospheric pressure substantiallybelow the vapor pressure of said solvent at the temperature of theprinting locus and immediately presenting said freshly printed surfacewithin said changer at a temperature below the boiling point of the inksolvent at normal atmospheric pressure and at a sufliciently reducedpressure to eflect ebullition of said vola tile solvent from the inkupon said surface while maintaining said printed surface out of contactwith relatively movable members until dry.

4. The method which comprises printing on a surface with an inkincluding a non-volatile color and a solvent having a boiling pointabove the temperature of the printing locus and transferring the freshlyprinted web into a reduced pressure zone at a temperature below theboiling point at normal atmospheric pressure of said solvent thepressure in said zone being sufficiently below the vapor pressure of theink solvent at the temperature of said zone to effect drying of theinked design by ebullition of said solvent said transferring beingaccomplished while supporting until dry the printed surface out of contoeffect ebullition of a volatile solvent from the ink.

6. A printing press including in combination a rotary printing couple,inking means therefor, means for presenting a web to said printingcouple to be imprinted thereby, a chamber and means for maintaining apartial atmospheric vacuum within the chamber of lower pressure than thevapor pressure of the ink solvent at the temperature of drying and meansfor directing the freshly printed web from the printing couple withinsaid chamber and subject to the reduced atmospheric pressure therewithinto effect ebullition of a volatile solvent from the ink.

7. A printing press including in combination a rotary printing couple,inking means therefon.

means for presenting a web to said printing couple to be imprintedthereby, an arcuate chamber of lower pressure than the vapor pressure ofthe ink solvent at the temperature of drying into and about which thefreshly printed web from the printing couple is directed and means formaintaining a partial vacuum within said chamber to effect ebullition ofa volatile solvent from the freshly imprinted ink on the web.

8. A printing press including in combination a rotary printing couple,inking means therefor, means for presenting a web to said printingcouple to be imprinted thereby, an arcuate chamber of lower pressurethan the vapofpressure of the ink solvent at the temperature of dryinginto and about which the freshly printed web from the printing couple isdirected and means for maintaining a partial vacuum within said chamberto effect ebullition of a volatile solvent from the freshly imprintedink on the web, said means comprising mechanism for exhausting air fromsaid chamber and closure devices located adjacent the points of entryinto and emergence of the web from the chamber.

9. A printing press including in combination a rotary printing couple,inking means therefor, means for presenting a web to said printingcouple to be imprinted thereby, and a chamber of lower pressure than thevapor pressure of the ink solvent at the temperature of drying formaintaining atmosphere at a reduced pressure comprising a drum aboutwhich the freshly printed web is directed, a housing spaced away fromand enclosing the greater part of said drum, means for exhausting airfrom the chamber between the drum and housing and closure deviceslocated adjacent the points of entry into and emergence of the web fromthe chamber, and means for directing a web into the chamber and aboutthe drum and out of the chamber at the other end thereof.

10. A printing press including in combination a printing couple, inkingmeans therefor, cooling means acting on the inking means to repressvoiatilization of the ink, a casing about the inking means to reduce aircirculation and evaporation, means for presenting paper to be imprintedby the printing couple, a chamber and means for maintaining a partialatmospheric vacuum of lower pressure than the vapor pressure of the inksolvent at the temperature of drying within the chamber and means forpresenting the freshly printed paper within he chamber and subject tothe reduced atmospheric pressure therewithin to effect ebullition of avolatile solvent from the ink.

HOBART N. DURHAM.

